Telephone impulse sender



Dec. 1 1941.

C. C. PUCKETTE TELEPHONE IMPULSE SENDER Filed May 15, 1940 Patented Dec. 16, 1941 TELEPHONE IMPULSE SENDER Charles Clarke Puckette, Coventry, England, assignor to The General-Electric Company Limited, London, England, a British company Application May 15, 1940, Serial No. 335,301 In Great Britain June 28, 1939 4 Claims.

The present invention relates to impulse senders of the type used in telephone systems and of the kind disclosed, for example, in my application, Serial No. 289,949, filed August 14, 1939, and the aim of the invention is the provision of means for ensuring silence in operation.

In impulse senders of this type, a rocking member is arranged to act upon impulse-producing contact springs, during the return motion of the finger plate only, by means of interaction between the rocking member and shaped impulseproducing teeth formed on a wheel fixed to the finger plate spindle. The rocking member, during both winding up and return motions of the finger plate, is alternately lifted and dropped by the teeth of the impulse-producing wheel, and unless special provision is made, a portion of the rocker drops to the bottom of each tooth gap, striking it and producing a click.

According to the present invention, an impulsing device of the type described is provided with a spring which co-operates with a portion of the rocker, the direction of action of the spring and the said portion of the rocker being so disposed and/or shaped, that the part of the rocker which is lifted by the impulse-producing teeth has a normal position clear of the root circle of the teeth.

In an embodiment of the invention, an impulse sender or dial of the type disclosed in the said application has the cam-faces of the rocker so shaped that the inner edge of the portion of the rocker which co-operates with the impulseproducing teeth is normally held just clear of the root circle of the said teeth, the rocker being lifted by the teeth during forward and return motions of the dial, though it acts on the impulse-producing contact springs only during the return motion.

Although, in the prior application, a felt washer is shown having a diameter slightly greater than the root circle of the teeth, and though it is stated that this washer acts both to lubricate the rocker bearings and to suppress noise, the modification of the dial stated to be the essence of the present invention renders this felt washer unnecessary for noise suppression, though it may still be fitted to ensure lubrication.

A noise which is occasionally apparent is that due to the arm which carries the rocker striking the bottom of the slot which limits its motion. This noise may be suppressed by cushioning the arm at the end of its travel. This may be performed either by arranging a rubber bufier on r 5, which itself is pivoted on the screw 6.

the arm or at the end of the slot, or by the use of a motion limiting spring or like buifering device.

A further click may be produced when the finger plate reverses its motion at the end of the wind-up period, due to the rocker slipping along the bottom of a tooth gap. It may be arranged to prevent this by providing small corrugations or teeth at the bottoms of the gaps.

In order that the nature of the invention may be more fully appreciated, reference should be made to the accompanying drawing in which Figure 1 is a part view of the lower side of an impulse sender, Figure 2 is a portion of an impulse producing wheel, Figure 3 is an end view of the rocker used in Figure 1, Figure 4 is another end view of an alternative type of rocker, Figure 5 is a similar view to Figure 3 but showing a different method of silencing the rocker-carrying arm, and Figure 6 is a diagrammatic view of a portion of the rocker, shown in the position it occupies during the winding up motion of the impulse sender.

Referring to Figures 1 and 6, it will be seen that an impulse sender similar to that shown in the application previously referred to is provided with an impulse-producing wheel I fastened to a central shaft 2 which carries a finger plate of known type (not shown). When this finger plate is rotated in a winding-up direction, that is counterclockwise in Fig. 1, the first tooth of the wheel I engages with the rocker 4, moving it to the position shown in Figure 6. This rocker is pivoted on a pin 3 carried by an arm The rocker and arm are held normally in the position shown by the spring 1, this position being such that the spur 8 of the rocker rests just clear of the root circle of the teeth of the impulse wheel I. This is ensured by the angular dispositions of the cam faces on the rocker 4 and the end of the spring I. The travel of the arm 5 is limited by engagement of its end M with the bottom of slot I I. Thus during impulsing the spur 8 of the rocker only rests against the bottom of a slot on the impulse-producing wheel during the initial parts of the wind-up and return motions. While the rocker is moving up and down under the influence of the teeth I during return of the finger plate and associated impulse wheel to normal, thus producing impulsing by co-operation of the insular l2 with the impulse springs l3, the spur 8 does not drop fully to the bottom of each slot in the impulse wheel, so that clicks due to this cause are eliminated. This arrangement also enables the felt ring adopted for noise suppression and oiling in the prior arrangement to be omitted from the construction, if required.

A further source of noise in an impulse sender of the type shown is that which occurs when the arm returns to the bottom of the slot ll during the winding-up or the return motion of the impulse sender. This noise may be suppressed as shown in either Figures 3, 4 or 5. Referring to Figure 3, it will be seen that the arm 5 carrying the pivot pin 3 and the trigger 4 has an extension l4 projecting through the slot H. This extension carries a rubber buffer l5, so that when the arm is moved in the slot and allowed to return to the position shown, to which it is biassed by the spring 1, the buffer l5 prevents the occurrence of any click caused by sudden engagement of two metal surfaces.

Figure 5 shows a very similar arrangement, except that this time the projection l4 engages with the edge of a rubber washer [6, the latter being fixed to the frame 20 of the impulse sender by the rivet II. This alternative provides a slightly lighter moving mass, but is not mechanically preferable.

A still further alternative is shown in Figure 4. In this figure, the extension M of the arm 5 rests normally against a spring I8 fixed to the frame 20 of the impulse sender. In such a position, the extension Hi just clears the bottom of the slot II, and the spring I8 is held clear of the pin [9. When the arm is lifted by the rocker, the extension l4 moves away from spring l8, which is then restricted in its following-up movement by the pin Hi. This arrangement, though avoiding the use of rubber, may still permit very faint clicks due to contact between the moving members.

A still further click which may occur during impulse sending, is that produced by the slipping of the spur 8 along the bottom of a slot on the impulse wheel I. This slipping takes place during the initial parts of the wind-up and return motions respectively. This click may be avoided either by making the bottoms of the slots curved as shown in Figure 1, or by providing small teeth 2| on the'impulse wheel I as shown in Figure 2. With the arrangement shown in Figure 1, the spur slides silently along the bottom of any slot in which it happens to be, whereas in Figure 2 the spur does not slip at all but engages with one or other of the teeth until the rocker is removed from the slot by the spring I.

I claim:

1. In an impulse sending mechanism, impulse contacts, a shaft carrying a finger wheel and a multiple cam, a rocker arm pivoted adjacent said cam, a pawl pivoted on said arm and engaged by the teeth of said cam when rotated by the wheel in both directions of its movement, a hub for said pawl encircling the pivot thereof and having flat faces lying in difierent planes, a spring engaging one of said surfaces to prevent the pawl from engaging the root of the cam teeth when the cam is rotated in one direction and said spring engaging another of the flat surfaces of said hub to prevent engagement of the pawl with the root of said cam teeth when the cam is rotated in the other direction, said pawl operated by said cam teeth to cause operation of said impulse contacts when the cam moves in one direction.

2. In an impulse sender, impulse contacts, a pawl, a finger wheel and a multiple cam movable together forward and back to cause said pawl to operate said contacts on the back movement of the cam only, said pawl pivotally mounted and movable by said cam through an arc on both the initial forward and on the intial backward movement of the cam, said pawl moved through a lesser are by the cam teeth on the forward and back movement subsequent to said initial movements, and a spring continuously engaging said pawl to prevent its engagement with the root of said cam teeth on the said subsequent movements.

3. A sender such as claimed in claim 2 in which there is a rocker arm pivotally mounted adjacent said cam, and in which the said pawl is pivotally mounted on the movable end of said arm.

4. A sender such as claimed in claim 2 in which there is a base plate supporting said cam and wheel, and having a rocker arm pivotally mounted' on said plate adjacent said cam and supporting the said pawl, a slot in said plate, and a pin on said arm movable in said slot and its movement limited thereby upon the initial movement of said cam, and resilient material asociated with said pin and slot to prevent clicks caused by movement of the pin in the slot.

CHARLES CLARKE PUCKETTE. 

